Packet switched networks are now widely used for voice communication. The Internet, with its widespread and affordable accessibility, has become a desirable and increasingly popular vehicle for such voice communication. For example, Voice over Internet Protocol (VoIP) allows for voice communication between devices (such as a computer or appropriately configured digital telephone) over the Internet Protocol (IP) commonly used in data transmission over the Internet. VoIP has become increasingly popular as it offers a number of advantages over traditional circuit switched networks in areas such as cost and flexibility.
Voice communication over the Internet has conventionally required the use of fixed (unchanging) internet protocol (IP) addresses to identify the locations of and route the voice data between the communicating devices during a call. For example, VoIP utilizes the Session Initiation Protocol (SIP) which establishes and manages a voice communication session using IP addresses of the devices that have been registered with a SIP server. A calling device obtains from the SIP server the IP address of a device to be called and then, if the call is answered and engaged, sends voice data packets to that IP address. The called device similarly obtains the IP address of the calling device and sends voice packets to that IP address in a similar fashion.
With the increasingly widespread use of mobile communication devices such as personal digital assistants (PDAs) and mobile telephones with Internet access it becomes desirable to provide their users with the ability to utilize the Internet in voice communication. Such mobile devices, however, are typically deployed on wireless carrier networks that require them to have, due to their mobility, dynamic (potentially changing) IP addresses. This renders them inappropriate for reliable voice communication over the Internet for which fixed IP addresses are normally utilized as described above.
In a VoIP call utilizing SIP, for example, if the IP address of a first communication device changes, voice packets sent by a second communication device would continue to be sent to the old IP address and thus would not be received by the first communication device. Furthermore, the second communication device would not recognize packets received from the new IP address as being from the first communication device. At that point, communication could not continue until the call is re-established. Such an interruption creates an undesirable disruption in the flow of communication, causes time-consuming delays and, where critical subject matter is being communicated, could have serious consequences.
A means is therefore desired for communicating fixed IP address based voice data in a dynamic IP address based communication environment.